U.S. Pat. No. 6,269,014 discloses a half-bridge circuit. Half-bridge circuits are is used in various power applications such as synchronous buck converters, resonant converters, electronic ballasts, induction heating and motion control, and offers such benefits as four-quadrant switching, zero-voltage switching (ZVS), zero-current switching (ZCS), high-frequency operation, low EMI and high efficiency. Half bridge circuits comprise an upper or high-side and lower or low-side power switch (typically MOSFETs) connected in a cascode arrangement between a positive and negative voltage supply, the node common to the low-side switch and the high-side switch being connected to drive a load.
In classical vertical power semiconductor technology, such as disclosed in U.S. Pat. No. 6,269,014, the high current switches have to be implemented on separate power dices. However, for the half-bridge the drain of the high side switch has to be connected to the source of the low-side switch to allow them to be switched on complementary to each other. This inhibits the low-side switch and the high-side switch being on the same die because in vertical power semiconductors the drain terminal of the power switch is the backside of the die, i.e. the semiconductor substrate bottom, itself. Accordingly, the drain is common for all the power devices on the same die.